How about something to make your blades sharp in the dark?
Casting Time: 1 action
Components: V, S
Duration: 1 hour
You touch a weapon. Until the spell ends, your weapon attacks score a critical hit on a roll of 19 or 20.
At Higher Levels: When you cast this spell using a spell slot of 6th level or higher, your weapon attacks score a critical hit on a roll of 18 or 20.